Software program engineer Joseph Naberhaus has taken a break from his ordinary interest of woodworking to deal with one thing completely different: the creation of a practical eight-bit laptop constructed utilizing discrete 7400-series logic chips.
“Earlier this yr,” Naberhaus explains, “I got here again from a tenting journey with an inspiration to study electronics. I began studying a textual content e-book, Sensible Electronics for Inventors, and started accruing gear. After constructing some fundamental frequency filters, I had the will to deal with a considerable mission. For a few years, I’ve dreamed about constructing a working laptop from simply logic gates. I ordered some breadboards, jumper cables, and built-in circuits and set to work.”
So far as first initiatives go, constructing a pc from discrete logic chips is an formidable one. The invention of the microprocessor was a breakthrough for compact computing, taking programs from room- or at finest desk-size into compact bins you can moderately have within the dwelling. Stepping again from that to create an equal utilizing solely AND, OR, NOT, NAND, and XOR gates is an actual problem — however one Naberhaus tackled with relish.
“With sufficient logic gates you may replicate any laptop on the earth,” Naberhaus explains. “The pc I constructed, alternatively, used solely about 800. I cheated in two locations. For each this system reminiscence and the RAM I used flash reminiscence chips. This implies I am unable to say I wired all the laptop by hand. Whereas this pains me to confess, I wasn’t keen to take a position the time or cash to treatment it.”
The system’s features are cut up throughout breadboards, with a wire bus working between them. (📷: Joseph Naberhaus)
The pc — which splits its varied core features throughout a number of breadboards for modularity — is programmed utilizing a customized meeting language Naberhaus developed for the mission, which compiles into 24-bit machine code. “Whereas the remainder of the pc makes use of 8-bit busses,” he explains, “I made a decision to splurge on the machine language for 2 causes. First, it allowed me to implement a richer set of directions. Second, it made implementing the directions less complicated.”
The completed system, which has 256 bytes of reminiscence, 256 traces of program reminiscence, and a clock pace of 500kHz, is detailed on Naberhaus’ web site and within the video embedded above and on the maker’s YouTube channel.